[avalanche] Clarify some conflicting options for stakers

Summary:
This makes it clear that the options are not compatible with a staking node.

Depends on D14969.

Test Plan:

./test/functional/test_runner.py abc_feature_avalanche_options

Reviewers: #bitcoin_abc, PiRK

Reviewed By: #bitcoin_abc, PiRK

Differential Revision: https://reviews.bitcoinabc.org/D14970